1. Field of the Invention
The present application generally relates to reclosable fasteners with sliders particularly suited for thermoplastic bags and the like. Particularly, the present application relates to a rolling action fastener with increased seal strength.
2. Description of Related Art
A reclosable fastener for thermoplastic bags or the like include a pair of male and female tracks with interlocking rib and groove elements. Generally, two types of such reclosable fasteners exist—(i) push to close (“PTC”) and (ii) zipper. The PTC fastener requires the application of an external force to open or close the engageable tracks, whereas the zipper fastener relies upon a slider for opening or closing the rib and groove elements. As such, the profile configuration of the reclosable track of a zipper fastener differs from that of a PTC fastener.
In the manufacture of thermoplastic film bags, a pair of these male and female fastener elements or tracks extend along the mouth of the bag and these male and female elements are adapted to be secured in any suitable manner to the flexible walls of the thermoplastic film bag. These elements may be integral marginal portions of such walls or the elements may be extruded separately and thereafter attached to the walls along the mouth of the bag. U.S. Pat. No. 5,007,143, which is incorporated by reference in its entirety, describes a zipper profile in which the cross-sectional shape of the zipper is such that the male and female elements can be engaged or closed by pressing the bottom together first, then rolling it closed toward the top. This configuration is referred to as a “rolling action” reclosable fastener.
However, there is a continued need to improve the seal strength of such conventional fasteners, yet still permitting the fasteners to be easily opened and closed.